Chapter 2

The total number of structural isomers of \(\mathrm{C}_{4} \mathrm{H}_{11} \mathrm{~N}\) would be (a) 4 (b) 8 (c) 5 (d) 10

How many geminal dichloride with different formula are possible for \(\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{Cl}_{2}\) ? (a) only one (b) two (c) three (d) four

What is the relation between 3-ethylpentane and 3-methylhexane? (a) Chain isomers (b) Position isomers (c) Functional isomers (d) Metamers

The compounds \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{~N}\) and \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\) represent (a) chain isomerism (b) position isomerism (c) functional isomerism (d) all of the above

An isomer of ethanol is (a) methanol (b) acetone (c) diethyl ether (d) dimethyl ether

The number of primary, secondary and tertiary amines possible with the molecular formula \(\mathrm{C}_{3} \mathrm{H}_{9} \mathrm{~N}\) respectively (a) \(1,2,2\) (b) \(1,2,1\) (c) \(2,1,1\) (d) \(3,0,1\)

Identify specific rotation of a mixture have \(5 \mathrm{~g}\) of \((+) 2\) -butanol and \(7 \mathrm{~g}\) of \((-) 2\) -butanol (If specific rotation of \(100 \%\) pure compound is \(13.5^{\circ}\) ) (a) \(-2.25^{\circ}\) (b) \(-1.6^{\circ}\) (c) \(12.2^{\circ}\) (d) \(4.45^{\circ}\)

Which compound is not the isomer of 3 -ethyl-2-methylpentane?

Identify compounds that give geometrical isomerisation

Which conformation has a \(\mathrm{C}_{3}\) axis of symmetry? (a) Boat (b) Twist boat (c) Chair (d) Enveloped

Which of the following can show tautomerism? (a) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CNO}\) (b) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}\) (c) \(\mathrm{R}_{3} \mathrm{CNO}_{2}\) (d) \(\mathrm{RCH}_{2} \mathrm{NO}_{2}\)

Choose the total number of constitutional isomers with the formula \(\mathrm{C}_{4} \mathrm{H}_{10} \mathrm{O}\). (a) 9 (b) 7 (c) 5 (d) 3

Which will not show tautomerism? (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NO}_{2}\) (b) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-\mathrm{CH}_{2} \mathrm{NO}_{2}\) (c) (d) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{NO}_{2}\)

Which of the following compound show tautomerism? (a) \(\left(\mathrm{H}_{3} \mathrm{C}\right)_{2} \mathrm{CCl}-\mathrm{CH}=\mathrm{CH}_{2}\) (b) O=Cc1ccccc1 (c) \(\left(\mathrm{H}_{3} \mathrm{C}\right)_{2} \mathrm{C}\left(\mathrm{NO}_{2}\right)-\mathrm{CH}=\mathrm{CH}-\mathrm{CHO}\) (d) None of these

In which structure Gauche form has less potential energy than antiform (a) \(\mathrm{CH}_{3}-\mathrm{CH}_{2}+\mathrm{CH}_{2}-\mathrm{Cl}\) (b) \(\mathrm{HO}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{F}\) (c) \(\mathrm{CH}_{2}\) ) \(\mathrm{CH}_{2}\) (d) \(\mathrm{HO}-\mathrm{CH}_{2}+\mathrm{CH}_{2}-\mathrm{OH}\)

Tautomerism will be exhibited by (a) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}\) (b) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CNO}\) (c) \(\mathrm{R}_{3} \mathrm{CNO}_{2}\) (d) \(\mathrm{RCH}_{2} \mathrm{NO}_{2}\)

Which of the following is not an example of tautomeric equilibrium? (a) \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{C}=\mathrm{O} \rightleftharpoons \mathrm{CH}_{2}-\mathrm{CH}=\mathrm{C}-\mathrm{O}\) (b) \(-\mathrm{N}=\mathrm{N}-\mathrm{NH} \rightleftharpoons \mathrm{NH}-\mathrm{N}=\mathrm{N}\) (c) \(>\mathrm{CH}-\mathrm{N}=\mathrm{O} \rightleftharpoons>\mathrm{C}=\mathrm{N}-\mathrm{OH}\) (d) \(-\mathrm{NH}-\mathrm{C}=\mathrm{O} \rightleftharpoons-\mathrm{N}=\mathrm{C}-\mathrm{OH}\)

Geometrical isomers differ in (a) position of functional group (b) spatial arrangement of atoms (c) position of atoms (d) length of carbon chain

Stereoisomers have different (a) Molecular formula (b) Structural formula (c) Configuration (d) Molecular mass

Which compound can show geometrical isomerism? (a) \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{C}\left(\mathrm{CH}_{3}\right)_{2}\) (b) \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}\) (c) \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{3}\) (d) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{C}\left(\mathrm{CH}_{3}\right)_{2}\)

The number of geometrical isomers in the following compound is \(\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}-\mathrm{C}_{2} \mathrm{H}_{5}\) (a) 4 (b) 3 (c) 2 (d) 5

Identify compound(s) in which gauche conformer is more stable than staggered (a) 1,2 -difluoroethane (b) Chloropropane (c) Ethylene glycol (d) Succinic acid

What characteristic is the best common to both cis-2-butene and trans-2-butene? (a) B.P. (b) Dipole moment (c) Heat of hydrogenation (d) Product of hydrogenation

The number of optically active compounds in the isomers of \(\mathrm{C}_{4} \mathrm{H}_{9} \mathrm{Br}\) is (a) 1 (b) 2 (c) 3 (d) 4

The number of optically active isomers observed in 2,3 -dichlorobutane is (a) 0 (b) 2 (c) 3 (d) 4

The instrument which can be used to measure optical activity, i.e., specific rotation (a) Refractometer (b) Photometer (c) Voltmeter (d) Polarimeter

Identify the structure of Erythro-butane-2, 3-diol

The enantiomeric excess and observed specific rotation of a mixture containing \(6 \mathrm{~g}\) of \((+)-2\) -butanol and \(4(\mathrm{~g})\) of \((-)-2\) -butanol are respectively (If the specific rotation of enantiomerically pure \((+)-2\) -butanol is \(+13.5\) units) (a) \(80 \%\), \(+2.7\) unit (b) \(20 \%,-27\) unit (c) \(20 \%,+2.7\) unit (d) \(80 \%\), \(-27\) unit

Which of the following pair of isomers cannot be separated by fractional crystallisation or fractional distillation? (a) Maleic acid and fumaric acid (b) (+)-Tartaric acid and meso-tartaric acid (c) \(\mathrm{CH}_{3}-\mathrm{CH}-\mathrm{COOH}\) and \(\mathrm{H}_{2} \mathrm{~N}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{COOH}\) CC(N)C(=O)O (d) ( \(+\) )-lactic acid and (-)-lactic acid

Increasing order of stability among the three main conformation (i.e., eclipse, anti, gauche) of ethylene glycol is (a) Eclipse, gauche, anti (b) Gauche, eclipse, anti (c) Eclipse, anti, gauche (d) Anti, gauche, eclipse

In the Newman projection formula of the least stable staggered form of \(\mathrm{n}\) -butane, which of the following reasons is the causes of its unstability? (a) Van der Waal's strain (b) Torsional strain (c) Combination of both (d) None of these

The dihedral angle between two methyl groups in partially eclipsed conformation of n-butane is (a) \(180^{\circ}\) (b) \(120^{\circ}\) (c) \(90^{\circ}\) (d) \(109^{\circ} 28^{\prime}\)

Evaporation of an aqueous solution of ammonium cyanate gives urea. This reaction follows the class of (a) Polymerisation (b) Isomerisation (c) Association (d) Dissociation

The possible number of alkynes with the formula \(\mathrm{C}_{5} \mathrm{H}_{8}\) is (a) 2 (b) 3 (c) 4 (d) 5

How many isomers of \(\mathrm{C}_{5} \mathrm{H}_{11} \mathrm{OH}\) will be primary alcohols (a) 2 (b) 3 (c) 4 (d) 5

Identify the compounds that give trans product on reaction with alcoholic KOH and heat

Number of isomeric forms of \(\mathrm{C}_{7} \mathrm{H}_{9} \mathrm{~N}\) having benzene ring will be (a) 7 (b) 6 (c) 5 (d) 4

Which of the following is an isomer of diethyl ether (a) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{COH}\) (b) \(\mathrm{CH}_{3} \mathrm{CHO}\) (c) \(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH}\) (d) \(\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \mathrm{CHOH}\)

Total number of isomeric alcohols with the formula \(\mathrm{C}_{4} \mathrm{H}_{10} \mathrm{O}\) is (a) 1 (b) 2 (c) 3 (d) 4

Different spatial arrangements of the atom that result from restricted rotation about a single bond are conformers. The general stability order of these conformer are as follows. Anti \(>\) Gauch \(>\) Partially eclipsed \(>\) Fully eclipsed Although anti is more stable than gauch but in some cases gauch is more stable than anti. Number of possible stable conformers of butane is (a) 2 (b) 4 (c) 6 (d) Infinite

The molecular formula of a saturated compound is \(\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Cl}_{2}\). The formula permits the existence of two (a) functional isomers (b) position isomers (c) optical isomers (d) cis-trans isomers

The type of isomerism found in urea molecule is (a) Chain (b) Position (c) Tautomerism (d) None of these

An alkane can show structural isomerism if it has ......... number of minimum carbon atoms (a) 1 (b) 2 (c) 3 (d) 4

How many chain isomers can be obtained from the alkane \(\mathrm{C}_{6} \mathrm{H}_{14} ?\) (a) 4 (b) 5 (c) 6 (d) 7

In the reaction: \(\mathrm{CH}_{3} \mathrm{CHO}+\mathrm{HCN} \longrightarrow \mathrm{CH}_{3} \mathrm{CH}(\mathrm{OH}) \mathrm{CN}\) a chiral centre is produced. The number of stereoisomers of the product is (a) 3 (b) 2 (c) 4 (d) none of these

Among the following conformers, which has highest potential energy for \(\mathrm{n}\) -butane (along \(\mathrm{C}_{2}-\mathrm{C}_{3}\) bond rotation)? (a) Skew (b) Fully eclipsed (c) Staggered (d) Partially eclipsed

The molecule 3 -penten-2-ol can exhibit (a) Optical isomerism (b) Geometrical isomerism (c) Metamerism (d) Tautomerism The correct answer is (a) (a) and (b) (b) (a) and (c) (c) (b) and (c) (d) (a) and (d)

Find the total number of isomers (including stereo isomers) in dimethyl cyclopropane and dimethyl cyclobutane (a) 6,8 (b) 5,6 (c) 4,5 (d) 4,6

Racemic mixture is formed by mixing two (a) Isomeric compounds (b) Chiral compounds (c) Meso compounds (d) Enantiomers

Which of the following does not show geometrical isomerism? (a) 1,2 -dichloro-1-pentene (b) 1,3 -dichloro-2-pentene (c) 1,1-dichloro-1-pentene (d) 1,4 -dichloro-2-pentene